AlternativeTo - AlternativeTo lets you find apps and software for Windows, Mac, Linux, iPhone, iPad, Android, Android Tablets, Web Apps, Online, Windows Tablets and more by recommending alternatives to apps you already know.

App Annie - App Annie is a marketing analytics tool available for apps of all kinds. With App Annie, you can track sales, traffic, and a variety of other factors pertinent to monitoring an app's trajectory.

SimilarSites - Easily find more sites like those you like.

AppFollow - AppFollow is an integrated solution that makes monitoring, analyzing, and elevating your app's reputation easy.

Product Hunt - A website that lets users share and discover new products

Sensor Tower - Sensor Tower is a platform for app store optimization and app industry intelligence.